Pullulan, a starting raw material for silylated pullulan, is a natural polysaccharide formed of maltotriose units regularly joined together via α-1,6-linkages. This pullulan is excellent in moisturizing properties, adhesion properties and safety, and as a nonionic polymer, is used as various additives.
For example, a derivative obtained by introducing silyl groups as side chains in the nonionic polymer is soluble in silicone oil, and the resulting solution is low in biological irritancy. Therefore, the derivative is expected to find utility in applications such as cosmetics, foods and medicines, and its use as an ingredient in foundations and makeup cosmetic preparations for nails is described in Patent Document 1.
In Patent Document 1, silylated pullulan is also exemplified as a derivative with silyl groups introduced as side chains in the nonionic polymer. Specifically, a process is disclosed, which includes dispersing pullulan in a mixed solvent of pyridine and toluene and then reacting it with triethylbromosilane. In addition, Patent Document 2 describes sunscreen cosmetic preparations with silylated pullulan mixed therein, and Patent Document 3 describes oil-based foundations with silylated pullulan mixed therein.
Patent Document 1: JP-A-62-240335
Patent Document 2: JP-B-3491933
Patent Document 3: JP-A-09-188604